Exercise Science and the Vocalist

Phonatory Tasks and Outcome Measures for Assessing Vocal Fatigue: A Scoping Review

OBJECTIVES

To map the phonatory tasks and the result measures used to evaluate vocal fatigue in vocally healthy individuals.

METHODS

This is a scoping review based on the following research question: What are the phonatory tasks and outcome measures used for the evaluation of vocal fatigue in vocally healthy individuals? The construction of the search strategy followed the PCC strategy; population: vocally healthy adult individuals; concept: phonatory tasks and vocal evaluation measures; and context: vocal fatigue. The search was performed electronically in the databases Medline (PubMed), LILACS (BVS), SCOPUS (Elsevier), Web of Science (Clarivate), EMBASE, and COCHRANE. A manual search in the references of the selected articles and in the journal with the highest number of publications was also performed. The selection of articles was based on reading the titles, abstracts, and full text, applying the eligibility criteria. The selected articles were related to the evaluation of vocal fatigue in healthy individuals from a predetermined vocal load task. Data regarding the characteristics of the publication, sample, phonatory tasks, and outcomes were extracted. The results were presented in a descriptive format, due to a frequency distribution analysis.

RESULTS

In total, 3756 studies were identified during the search, of which 60 were selected. The most used vocal load activity was the reading task, with duration ranging from 46 to 120 minutes. The (1) sustained vowel /a/ and (2) the reading of texts and phrases, both in usual intensity and frequency without the interference of the researcher, were the most used evaluation tasks. The most used outcome measures are the following: (1) acoustic parameters-fundamental frequency [fo] (mean, variance), sound pressure level (mean), local jitter (%), local shimmer (%), cepstral peak prominence (mean); (2) vocal self-assessment by the validated instruments-Perceived Phonatory Effort Scale, Visual Analog Scale, Borg-CR-10 Scale.

CONCLUSIONS

There is a diversity of phonatory tasks and outcome measures recurrently used in scientific articles to evaluate the signs of vocal fatigue in vocally healthy individuals. The most used vocal sample to evaluate vocal fatigue was the sustained vowel /a/ in habitual intensity and frequency without the interference of the researcher. The most frequently reported outcome measures for the assessment of immediate vocal fatigue effects were the acoustic analysis and vocal self-assessment.

A Systematic Review of Speech-Language Pathology Interventions for Presbyphonia Using the Rehabilitation Treatment Specification System

BACKGROUND

The prevalence of voice disorders for people aged >65 years is four times higher than for the population at large. The most common cause of dysphonia in this group is presbyphonia, the preferred first-line treatment for which is voice therapy with a speech-language pathologist. This systematic review seeks to identify how voice therapy affects multidimensional voice outcomes in people with presbyphonia.

METHODS

A systematic search of CINAHL, Embase, Emcare, MEDLINE, and Google Scholar was conducted in March 2023. Comparative and noncomparative studies of voice therapy in participants aged >50 years with presbyphonia were considered for inclusion. No limitations were placed on date or language of publication. Study quality and risk of bias were assessed with the Cochrane Risk of Bias 2 tool and the Methodological Index for Non-Randomized Studies. Subgroup analysis was used to compare studies based on participant sex, intervention duration, study design, and intervention content. Interventions were specified using the Rehabilitation Treatment Specification System (RTSS) employing a consensus methodology among reviewers. The results were synthesized utilizing meta-analysis when outcomes were adequately specified and narrative analysis when they were not.

RESULTS

Twenty-three studies were included with 1050 subjects (mean age: 72.5 ± 8.6 years; 51% female). The most reported intervention was vocal function exercises. Per the RTSS, 14 interventions employed a predominantly Organ Functions approach, and the 14 remaining interventions employed a Skills & Habits approach. Meta-analysis confirmed posttherapy improvement in patient-related outcome measures of 0.93 standard mean difference (P < 0.00001, 95% confidence interval [CI]: 0.70-1.17); studies with predominantly males and with longer treatment periods were associated with larger improvements, while randomized controlled trials reported more modest improvements. Meta-analysis also identified a mean posttherapy increase in maximum phonation time (MPT) of 5.37 seconds (P < 0.00001, 95% CI: 3.52-7.22). Treatments with an Organ Functions focus resulted in greater gains in MPT than those with a Skills & Habits focus (7.52 seconds versus 2.90 seconds). Finally, meta-analysis identified reductions in acoustic perturbation measures (jitter: 0.62%, P < 0.001, 95% CI: 0.26%-0.97%; shimmer 1.05%, P < 0.00001, 95% CI: 0.67%-1.44%). Narrative synthesis further identified improvement in auditory-perceptual voice quality in all active treatment groups as well as improved glottal function in most studies that reported this.

CONCLUSIONS

Despite the uncertainty around internal validity introduced by the inclusion of a wide range of study designs, there is convincing evidence that voice therapy for presbyphonia results in significant improvement in patient-reported, aerodynamic, acoustic, and expert-rated voice outcomes. Treatments with an Organ Functions focus may better address the underlying physiological deficits of presbyphonia, although future comparative studies with multidimensional voice assessment are warranted.

Daily vocal exercise is necessary for peak performance singing in a songbird

Vocal signals, including human speech and birdsong, are produced by complicated, precisely coordinated body movements, whose execution is fitness-determining in resource competition and mate choice. While the acquisition and maintenance of motor skills generally requires practice to develop and maintain both motor circuitry and muscle performance, it is unknown whether vocal muscles, like limb muscles, exhibit exercise-induced plasticity. Here, we show that juvenile and adult zebra finches (Taeniopygia castanotis) require daily vocal exercise to first gain and subsequently maintain peak vocal muscle performance. Experimentally preventing male birds from singing alters both vocal muscle physiology and vocal performance within days. Furthermore, we find females prefer song of vocally exercised males in choice experiments. Vocal output thus contains information on recent exercise status, and acts as an honest indicator of past exercise investment in songbirds, and possibly in all vocalising vertebrates.

Peak performance singing requires daily vocal exercise in songbirds

Vocal signals mediate much of human and non-human communication. Key performance traits - such as repertoire size, speed and accuracy of delivery - affect communication efficacy in fitness-decisive contexts such as mate choice and resource competition 1 . Specialized fast vocal muscles 2,3 are central to accurate sound production 4 , but it is unknown whether vocal, like limb muscles 5,6 , need exercise to gain and maintain peak performance 7,8 . Here, we show that for song development in juvenile songbirds, the closest analogue to human speech acquisition 9 , regular vocal muscle exercise is crucial to achieve adult peak muscle performance. Furthermore, adult vocal muscle performance reduces within two days of abolishing exercise, leading to downregulation of critical proteins transforming fast to slower muscle fibre types. Daily vocal exercise is thus required to both gain and maintain peak vocal muscle performance, and if absent changes vocal output. We show that conspecifics can detect these acoustic changes and females prefer the song of exercised males. Song thus contains information on recent exercise status of the sender. Daily investment in vocal exercise to maintain peak performance is an unrecognized cost of singing and could explain why many birds sing daily even under adverse conditions 10 . Because neural regulation of syringeal and laryngeal muscle plasticity is equivalent, vocal output may reflect recent exercise status in all vocalizing vertebrates.

Metabolomic Expression of Laryngeal and Hindlimb Muscles in Adult versus Senescent Rats

OBJECTIVES

(1) Determine the feasibility of obtaining a global, unbiased metabolomic profile on laryngeal muscle in a rat model; (2) evaluate the impact of biological aging on the laryngeal metabolome; and (3) characterize biochemical expression differences between aged and non-aged laryngeal and hindlimb muscle.

METHODS

Thyroarytenoid laryngeal muscle and plantaris hindlimb muscle were harvested from 5 young adult (9 months old) and 5 older adult (32 months old) F344BN rats. Tissue was processed and analyzed using LC-MS methods. Detected metabolites were compared to widely used metabolite databases and KEGG pathway enrichment was performed on significant metabolites.

RESULTS

The greatest differences in metabolite expression were between laryngeal and limb muscle with 126 different metabolites found between laryngeal and limb within the young group and 149 different metabolites within the old group. Significant hits between muscle groups highlighted amino acid differences between these tissues. There were more robust differences with age in limb muscle compared to laryngeal muscle.

CONCLUSIONS

Amino acid metabolism is a key difference between muscles of the limbs and larynx. Due to the number of differentially expressed metabolites between the 2 muscle groups, caution should be exercised when applying skeletal limb muscle physiology and biology concepts to the vocal muscles in both aged and non-aged musculoskeletal systems. Mechanisms underlying less robust effects of age on laryngeal muscle compared to limb muscle require elucidation.

Quantifying Vocal Power: Correlation of Whole-Body Anaerobic Power to Vocal Function Measures

Purpose The purpose of this preliminary study was to identify a vocal task that could be used as a clinical indicator of the vocal aptitude or vocal fitness required for vocally demanding occupations in a manner similar to that of the anaerobic power tests commonly used in exercise science. Performance outcomes for vocal tasks that require rapid acceleration and high force production may be useful as an indirect indicator of muscle fiber complement and bioenergetic fitness of the larynx, an organ that is difficult to study directly. Method Sixteen women (age range: 19-24 years, M _age = 22 years) were consented for participation and completed the following performance measures: forced vital capacity, three adapted vocal function tasks, and the horizontal sprint test. Results Using a within-participant correlational analyses, results indicated a positive relationship between the rate of the last second of a laryngeal diadochokinesis task that was produced at a high fundamental frequency/high sound level and anaerobic power. Forced vital capacity was not correlated with any of the vocal function tasks. Conclusions These preliminary results indicate that aspects of the laryngeal diadochokinesis task produced at a high fundamental frequency and high sound level may be useful as an ecologically valid measure of vocal power ability. Quantification of vocal power ability may be useful as a vocal fitness assessment or as an outcome measure for voice rehabilitation and habilitation for patients with vocally demanding jobs.